1. Field of the Invention
The present invention is related to a power zoom lens, and a camera system having such a power zoom lens.
This application is related to commonly assigned applications U.S. Ser. Nos. 07/410,880, 07/652,038, 07/407,424, 07/414,477, 07/414,478, 07/670,733, 07/406,523, and 07/414,476, the disclosures of which are expressly incorporated by reference herein.
2. Description of Related Art
A power zoom lens and a camera system having an automatic focusing device and a power zoom device are known.
However, a power zoom type single lens reflex camera which has an interchangeable lens has not been marketed, since the provision of a zoom motor and a battery in the camera body makes the single lens reflex camera heavy and complicated, in comparison with a camera having a lens integral with the camera body. In a single lens reflex camera to which a zoom lens is mounted, the length of the zoom lens should be made as short as possible, when not in an operational state, for example, when the camera is transported by a photographer. To shorten the zoom lens, a photographer must actuate a zoom ring to move a lens barrel to its most retracted position. Namely, it is necessary for the photographer to effect the zooming operation to thereby move the lens barrel.
Furthermore, in a conventional power zoom lens, a photographer actuates a zoom switch to effect the power zooming operation in a telephoto direction or wide angle direction. However, if a photographer wants to adjust the focal lens to a frequently used focal length, then he or she must manually zoom the lens to locate the focal length which is frequently used.